Question

A body of mass of $100g$ is attached to a $1m$ long string and it is revolving in a vertical circle. When the string makes an angle of $60^{o}$ with the vertical then its speed is $2\mspace{6mu} m/s$. The tension in the string at $\theta = 60^{o}$ will be

• A. $89\mspace{6mu} N$
• B. $0.89\mspace{6mu} N$
• C. $8.9\mspace{6mu} N$
• D. $0.089\mspace{6mu} N$

Answer 1

Answer: (B)

$0.89\mspace{6mu} N$

Answer 2

$T = mg\cos\theta + \frac{mv^{2}}{r} = 0.1 \times 9.8 \times \cos 60 + \frac{0.1 \times (2)^{2}}{1} = 0.49 + 0.4 = 0.89Newton$